Field of the Invention
The present invention relates to a structure of a dust collecting filter provided, for example, at an exhaust duct in an image forming apparatus.
Description of the Related Art
An electrophotographic image forming apparatus is described as an example. In an apparatus main body of the image forming apparatus, electrical components, such as a plurality of motors, a fan, a power board, and a heater, are provided as components (e.g., unit configurations) for conveying sheets as recording media, forming an image, and then discharging a product.
The electrical components, such as motors, an electric board and a heater, generate heat from electrical component main bodies when they are driven to operate. The generated heat is accumulated in the apparatus main body to rise a temperature in the apparatus main body. The temperature rise may cause, for example, thermal deformation of components, such as a sheet conveyance guide made of plastic, disposed inside the apparatus main body. The thermal deformation may cause paper jam of conveyed sheets.
In some environments in which the image forming apparatus is installed, dust may be collected inside the apparatus main body, or dust may rise and fly due to, for example, vibration by the operation of the apparatus and airflow of the fan. Such dust may adhere, for example, to a surface of a sheet and cause a missing image when an image is transferred to the sheet. As a result, image quality may be reduced due to an image defect.
Then, a fan and a duct for purifying air inside and exhausting air (exhausting heat) from the apparatus main body are typically provided, and a filter for collecting dust is installed in a path of the duct.
PCT Japanese Translation Patent Publication No. 2007-516829 discloses the following filter assembly. A filter is installed in a base frame that has an installation portion for installing a pleat-shaped filter. A cover frame formed integrally with the base frame by a hinge is made to pivot about the hinge, and the filter is held between the base frame and the cover frame. Then, a projection for fitting provided in the cover frame is made to fit in a cantilever pillar member having a fitting hole provided in the base frame to close the base frame and the cover frame.
With this opening/closing configuration of the base frame and the cover frame, the filter that has caught dust and become unclean may be removed. Since the filter may be replaced with a new filter, a replacement operation at the time of maintenance may be simplified, which is advantageous.
Japanese Patent Laid-Open No. 11-63597 discloses the following filter assembly. That is, a plate-shaped filter is installed in a first frame on a side on which a filter having a cross flame is provided. A second frame formed integrally with the first frame by a hinge for holding the filter is folded about the hinge onto the first frame. A latching projection provided in the first frame latches a frame (i.e., a thin board) of the second frame. An engagement protrusion is provided in the second frame. An engaging hole of a bent piece formed integrally with the first frame by a hinge is folded about the hinge so that the engagement protrusion engages the engaging hole of the bent piece.
The filter assembly is thus obtained.
In the past, the entire filter assembly in which the frame and the filter are integrated with each other are replaced with a new filter assembly. With this filter configuration, however, the filter that has become unclean may be replaced with a new filter and, therefore, the running cost may be reduced.
The filter frame includes a latching projection that latches the filter frame not to open when the filter frame is closed. If the projections are provided on three sides of the filter frame other than the side on which the hinge is provided, it is required to release the latch of each of the three sides to open and close the filter frame when the filter is to be replaced.
In the filter assembly disclosed in PCT Japanese Translation Patent Publication No. 2007-516829, at the periodic replacement of an unclean filter, it is required to release the fitting, one by one, of the cantilever pillar member having the engaging hole provided in the base frame of the filter case from the engagement protrusion provided in the cover frame. Therefore, there is a problem that taking the unclean filter from the filter case takes time and labor.
In the filter structure disclosed in Japanese Patent Laid-Open No. 11-63597, when a new filter is installed in the filter case, the filter frame is made to fit by the fitting projection and the frame. After this operation, the bent piece having the engaging hole is further folded about the hinge so that the engaging hole is made to engage the engagement protrusion provided in the frame. The filter frame is thus assembled. When the unclean filter is removed, the above operation is performed in the reverse order. As described above, since a plurality of engaging portions need to be engaged or disengaged one by one, there is a problem that such operations take labor and time.